A theoretical model for grain-boundary sliding via intragranular dislocation slip was suggested by experimental results for Zn and Cd bi-crystals. The lattice dislocations of 2 grains were supposed to dissociate in the boundary so as to form 2 families of mobile grain boundary dislocations of opposite sign. The motion of grain boundary dislocations having a non-conservative component was the main mechanism of grain boundary sliding. The sliding rate was governed by the grain boundary dislocation density, and by their annihilation rate at sinks or surfaces. The increase in grain boundary dislocation density produced additional elastic fields, in the vicinity of the boundary, which inhibited the entry of lattice dislocations into the boundary and lowered the efficiency of the source. The grain boundary dislocation density balance, as determined by the ratio of the influx of lattice dislocations to the annihilation of grain boundary dislocations, was thus established. The boundary therefore exhibited negative-feedback behavior. This model permitted the grain boundary sliding time-dependence in Cd and Zn bi-crystals to be described and extended understanding, of the interaction of the various mechanisms, to the deformation of polycrystals.

The Model of Grain-Boundary Sliding Stimulated by Intragranular Slip A.I.Pshenichnyuk, V.V.Astanin, O.A.Kaibyshev: Philosophical Magazine A, 1998, 77[4], 1093-106